linux-stable.git/arch/mips/kernel/setup.c, branch v5.5

MIPS: Loongson64: Rename CPU TYPES

2019-10-31T22:03:10+00:00

CPU_LOONGSON2 -> CPU_LOONGSON2EF
CPU_LOONGSON3 -> CPU_LOONGSON64

As newer loongson-2 products (2G/2H/2K1000) can share kernel
implementation with loongson-3 while 2E/2F are less similar with
other LOONGSON64 products.

Signed-off-by: Jiaxun Yang 
Signed-off-by: Paul Burton 
Cc: linux-mips@vger.kernel.org
Cc: chenhc@lemote.com
Cc: paul.burton@mips.com

MIPS: Make builtin_cmdline const & variable length

2019-10-12T20:44:24+00:00

We have no need for the builtin_cmdline array to be fixed at the length
of COMMAND_LINE_SIZE - we'll only copy out the string it contains up to
its NULL terminator anyway, and cap the size at COMMAND_LINE_SIZE when
copying into or concatenating with boot_command_line.

The string value is also constant, so we can declare it as such to place
it in the .init.rodata section.

Signed-off-by: Paul Burton 
Cc: linux-mips@vger.kernel.org

MIPS: Fix CONFIG_OF_EARLY_FLATTREE=n builds

2019-10-12T20:44:23+00:00

Configurations with CONFIG_OF_EARLY_FLATTREE=n fail to build since
commit 7784cac69735 ("MIPS: cmdline: Clean up boot_command_line
initialization") because of_scan_flat_dt() & of_scan_flat_dt() are not
defined in these configurations. Fix this by #ifdef'ing the affected
code...

Signed-off-by: Paul Burton 
Fixes: 7784cac69735 ("MIPS: cmdline: Clean up boot_command_line initialization")
Reported-by: kbuild test robot 
Cc: linux-mips@vger.kernel.org

MIPS: Always define builtin_cmdline

2019-10-12T20:44:22+00:00

Commit 7784cac69735 ("MIPS: cmdline: Clean up boot_command_line
initialization") made use of builtin_cmdline conditional upon plain C if
statements rather than preprocessor #ifdef's. This caused build failures
for configurations with CONFIG_CMDLINE_BOOL=n where builtin_cmdline
wasn't defined, for example:

   arch/mips/kernel/setup.c: In function 'bootcmdline_init':
>> arch/mips/kernel/setup.c:582:30: error: 'builtin_cmdline' undeclared
    (first use in this function); did you mean 'builtin_driver'?
      strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
                                 ^~~~~~~~~~~~~~~
                                 builtin_driver
   arch/mips/kernel/setup.c:582:30: note: each undeclared identifier is
    reported only once for each function it appears in

Fix this by defining builtin_cmdline as an empty string in the affected
configurations. All of the paths that use it should be optimized out
anyway so the data itself gets optimized away too.

Signed-off-by: Paul Burton 
Fixes: 7784cac69735 ("MIPS: cmdline: Clean up boot_command_line initialization")
Reported-by: kbuild test robot 
Reported-by: Nathan Chancellor 
Cc: linux-mips@vger.kernel.org

MIPS: cmdline: Clean up boot_command_line initialization

2019-10-10T18:56:43+00:00

Our current code to initialize boot_command_line is a mess. Some of this
is due to the addition of too many options over the years, and some of
this is due to workarounds for early_init_dt_scan_chosen() performing
actions specific to options from other architectures that probably
shouldn't be in generic code.

Clean this up by introducing a new bootcmdline_init() function that
simplifies the initialization somewhat. The major changes are:

- Because bootcmdline_init() is a function it can return early in the
  CONFIG_CMDLINE_OVERRIDE case.

- We clear boot_command_line rather than inheriting whatever
  early_init_dt_scan_chosen() may have left us. This means we no longer
  need to set boot_command_line to a space character in an attempt to
  prevent early_init_dt_scan_chosen() from copying CONFIG_CMDLINE into
  boot_command_line without us knowing about it.

- Indirection via USE_PROM_CMDLINE, USE_DTB_CMDLINE, EXTEND_WITH_PROM &
  BUILTIN_EXTEND_WITH_PROM macros is removed; they seemingly served only
  to obfuscate the code.

- The logic is cleaner, clearer & commented.

Two minor drawbacks of this approach are:

1) We call of_scan_flat_dt(), which means we scan through the DT again.
   The overhead is fairly minimal & shouldn't be noticeable.

2) cmdline_scan_chosen() duplicates a small amount of the logic from
   early_init_dt_scan_chosen(). Alternatives might be to allow the
   generic FDT code to keep & expose a copy of the arguments taken from
   the /chosen node's bootargs property, or to introduce a function like
   early_init_dt_scan_chosen() that retrieves them without modification
   to handle CONFIG_CMDLINE. Neither of these sounds particularly
   cleaner though, and this way we at least keep the extra work in
   arch/mips.

Signed-off-by: Paul Burton 
Cc: linux-mips@vger.kernel.org

MIPS: init: Prevent adding memory before PHYS_OFFSET

2019-10-02T21:11:30+00:00

On some SGI machines (IP28 and IP30) a small region of memory is mirrored
to pyhsical address 0 for exception vectors while rest of the memory
is reachable at a higher physical address. ARC PROM marks this
region as reserved, but with commit a94e4f24ec83 ("MIPS: init: Drop
boot_mem_map") this chunk is used, when searching for start of ram,
which breaks at least IP28 and IP30 machines. To fix this
add_region_memory() checks for start address < PHYS_OFFSET and ignores
these chunks.

Fixes: a94e4f24ec83 ("MIPS: init: Drop boot_mem_map")
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Paul Burton 
Cc: Ralf Baechle 
Cc: James Hogan 
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

MIPS: init: Fix reservation of memory between PHYS_OFFSET and mem start

2019-10-02T21:10:16+00:00

Fix calculation of the size for reserving memory between PHYS_OFFSET
and real memory start.

Fixes: a94e4f24ec83 ("MIPS: init: Drop boot_mem_map")
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Paul Burton 
Cc: Ralf Baechle 
Cc: James Hogan 
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

mips: avoid explicit UB in assignment of mips_io_port_base

2019-08-24T14:10:58+00:00

The code in question is modifying a variable declared const through
pointer manipulation.  Such code is explicitly undefined behavior, and
is the lone issue preventing malta_defconfig from booting when built
with Clang:

If an attempt is made to modify an object defined with a const-qualified
type through use of an lvalue with non-const-qualified type, the
behavior is undefined.

LLVM is removing such assignments. A simple fix is to not declare
variables const that you plan on modifying.  Limiting the scope would be
a better method of preventing unwanted writes to such a variable.

Further, the code in question mentions "compiler bugs" without any links
to bug reports, so it is difficult to know if the issue is resolved in
GCC. The patch was authored in 2006, which would have been GCC 4.0.3 or
4.1.1. The minimal supported version of GCC in the Linux kernel is
currently 4.6.

For what its worth, there was UB before the commit in question, it just
added a barrier and got lucky IRT codegen. I don't think there's any
actual compiler bugs related, just runtime bugs due to UB.

Link: https://github.com/ClangBuiltLinux/linux/issues/610
Fixes: 966f4406d903 ("[MIPS] Work around bad code generation for .")
Reported-by: Nathan Chancellor 
Debugged-by: Nathan Chancellor 
Suggested-by: Eli Friedman 
Signed-off-by: Nick Desaulniers 
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor 
Signed-off-by: Paul Burton 
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: Maciej W. Rozycki 
Cc: Hassan Naveed 
Cc: Stephen Kitt 
Cc: Serge Semin 
Cc: Mike Rapoport 
Cc: Andrew Morton 
Cc: Michal Hocko 
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com

MIPS: Fix build with CONFIG_PROC_VMCORE=y

2019-08-23T17:02:49+00:00

Commit a94e4f24ec83 ("MIPS: init: Drop boot_mem_map") introduced a
reference to a non-existant "end" field in struct memblock_region.
Replace it with a sum of the base & size fields to fix builds with
CONFIG_PROC_VMCORE=y.

Reported-by: kbuild test robot 
Signed-off-by: Paul Burton

MIPS: init: Drop boot_mem_map

2019-08-23T14:42:40+00:00

boot_mem_map was introduced very early and cannot handle memory maps
with nid. Nowadays, memblock can exactly replace boot_mem_map.

Detect pfn info and setup resources with memblock maps.

Signed-off-by: Jiaxun Yang 
[paul.burton@mips.com: Fix size calculation in check_kernel_sections_mem]
Signed-off-by: Paul Burton 
Cc: linux-mips@vger.kernel.org
Cc: yasha.che3@gmail.com
Cc: aurelien@aurel32.net
Cc: sfr@canb.auug.org.au
Cc: fancer.lancer@gmail.com
Cc: matt.redfearn@mips.com
Cc: chenhc@lemote.com